02Apr2016

A Letter – Just In Time

clock

The email arrived a few days ago from a reader who wanted to know if time travel was possible, and if so, when it would most likely happen. The answer to this question is very simple…its basically a  case of yes, no and don’t know!

A contradiction? Yes, for sure, still the ideas are based on good, solid science. In all time travel theories allowed by real science, there is no way a traveller can go back in time to before the time machine was built. I am confident time travel into the future is possible, you simply move very fast…almost as fast as light, but we would need to develop some very advanced technology to do it.

Let’s look simply at this in an attempt to explain to you how it all stated , how the concept developed and who took part in its construction. A good physics retrospective if you’re that  way inclined.

Michelson-MorleyExperiment

michelson interferometer

Michelson-Morley experiment was an attempt to detect the velocity of the Earth with respect to the hypothetical ‘luminiferous’ ether, a medium in space proposed to carry light waves. First performed in Germany in 1880–81 by the physicist A.A. Michelson, the test was later refined in 1887 by Michelson and Edward W. Morley in the United States.

The procedure depended on a Michelson interferometer, a sensitive optical device that compares the optical path lengths for light moving in two mutually perpendicular directions.

It was reasoned that, if the speed of light were constant with respect to the proposed ether through which the Earth was moving, that motion could be detected by comparing the speed of light in the direction of the Earth’s motion and the speed of light at right angles to the Earth’s motion.

No difference was found. This null result seriously discredited the ether theories and ultimately led to the proposal by Albert Einstein in 1905 that the speed of light is a universal constant.

 Lorentz-FitzGerald Contraction

Lorentz-FitzGerald contraction, also called space contraction , in relativity physics, the shortening of an object along the direction of its motion relative to an observer. Dimensions in other directions are not contracted. The concept of the contraction was proposed by the Irish physicist George FitzGerald in 1889, and it was thereafter independently developed by Hendrik Lorentz of the Netherlands.

The Michelson-Morley experiment in the 1880s had challenged the postulates of classical physics by proving that the speed of light is the same for all observers, regardless of their relative motion. FitzGerald and Lorentz attempted to preserve the classical concepts by demonstrating the manner in which space contraction of the measuring apparatus would reduce the apparent constancy of the speed of light to the status of an experimental artefact.

In 1905 the German-American physicist Albert Einstein reversed the classical view by proposing that the speed of light is indeed a universal constant and showing that space contraction then becomes a logical consequence of the relative motion of different observers. Significant at speeds approaching that of light, the contraction is a consequence of the properties of space and time and does not depend on compression, cooling, or any similar physical disturbance.

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